"Medical Exemptions" are also a standard right in the State of Texas for motorcycles & even bicyclists. Through Texas's motorcycle helmet law (bicycle helmet laws from city ordinances), it is only required for those 21 years old or younger to wear a helmet. However, a medical exemption,  written by a certified licensed medical physician or licensed chiropractor, which exempts one from wearing a helmet, can be used for bicyclists if helmets are required.
Since 2001, Canada's Motor Vehicle Safety Regulations (MVSR) have defined Power Assisted bicycles (PABs). They are currently defined as a two or three wheeled bicycle with an attached electric motor of 500W or less and which is capable of being propelled manually. Furthermore to meet the safety requirements set down by this legislation it must meet the following; when engaged by muscular power it must cease assistance when muscular power ceases or if powered by an accelerator controller cease power when braking and be incapable of providing assistance above 32 km/h and bear a label that is permanently affixed by the manufacturer and appears in a conspicuous location stating the vehicle is a power-assisted bicycle.
I like this little electric "scooter" a lot. I do think the rear wheels should be a bit further apart for added stability. I have also found it is too easy to "spin out" the front driver wheel when going up an incline or crossing a grass area. The user and assembly manual is minimal and could use considerably more information and more and better illustrations.
"Moped" means a device upon which a person may ride which has two or three wheels in contact with the ground, a motor having a maximum power output capability measured at the motor output shaft, in accordance with the Society of Automotive Engineers standards, of two horsepower (one thousand four hundred ninety -two watts) or less and, if it is a combustion engine, a maximum piston or rotor displacement of 3.05 cubic inches (fifty cubic centimeters) and which will propel the moped, unassisted, on a level surface at a maximum speed no greater than thirty miles per hour; and a direct or automatic power drive system which requires no clutch or gear shift operation by the moped driver after the drive system is engaged with the power unit.
I purchased version 2.0 of this device and the manufacturer has been listening to comments from users and making running changes such as the three speeds and the rear suspension. I am an XL size user (6'2", 230lbs) and recently returned from a 26 day cruise around Europe. I rode this little scooter on cobblestones, miles and miles through the Vatican, inside ancient cities and all over the streets of San Juan upon our return stateside. There was only one time it was less than ideal and that was going uphill, on slick tile that was wet from a drizzle. It still make it, just had to lean way forward to get weight on the front wheel.
When I began testing the Rad Power bike, I wasn’t sure if it would ride like a bakfiets or more like your standard bike. Hundreds of miles later, the RadWagon’s biggest strength is how well it handles. If you aren’t riding with kids, you almost never notice the weight of the cargo area behind you and pedaling is made easy and efficient thanks to a 750W direct drive hub motor and smooth acceleration.
Every person riding a bicycle, electric personal assistive mobility device, electric power-assisted bicycle, moped, or an animal or driving an animal on a highway shall be subject to the provisions of this chapter and shall have all of the rights and duties applicable to the driver of a vehicle, unless the context of the provision clearly indicates otherwise.